Redirecting deflected boreholes



Aug. 30, 1960' A. c. WYNES REDIRECTING DEFLECTED. BOREHOLES 4 Sheets-Sheet 1 Filed Oct. 11. 1956 a 6M ,2. M, Rm w 0 a v 67/47/44 427/? swwg 5 A. c. WYNES REDIRECTING DEFLECTED BOREHOLES Aug. 30, 1960 4 Sheets-Sheet 2 Filed Oct. ll. i956 F [Y n I I IN hHl h In a W////////@ I I I 4 .....m.n..n.n...n.w w M F 1 1 w 7 9 5 W 0 "Finn v 620?. 9 \w W ml m l X w I! It! 2 I .A IIIJ... I

Aug. 30, 1960 A. c. WYNES REDIRECTING DEFLECTED BOREHOLES 4 Sheets-Sheet 3 Filed Oct. 11. 1956 Am www A. C. WYNES REDIRECTING DEIF'LECTED BOREHOLES Aug. 30, 1960 4 Sheets-Sheet 4 Filed Oct. 11. 1956 United States Patent O REDIRECTING DEFLECTED BOREHOLES Alfred C. 'Wynes, 28 7th Ave., Nkana, Northern Rhodesia Filed Oct. 11, 1956, Ser. No. 615,389

Claims priority, application Union of South Africa Oct. 13, 1955 '7 Claims. (Cl. 25'51.6)

This invention relates to apparatus for the redirection of deflected boreholes to guide them nearer to verticality.

In known procedures relating to drills and boreholes a device may be lowered into a borehole and anchored therein to provide a path that is more nearly vertical than the hole itself, the drill being coerced along said path.

The device may be located by careful orientation on lowering means, as in the case of the well-known whipstock in oil drilling. Alternatively the aid of gravity may be invoked as in the case of a device in which a pilot drill is freely suspended and rotated to pierce the bottom of the hole. The shank of the pilot drill is then used as a guide for the drill.

The object of the present invention is to provide an arrangement which facilitates accurate drilling and is uncomplicated and easy to handle.

According to the invention, the redirecting of a'deflected borehole nearer to verticality involves suspending from a drill rod line a deflector, providing the guide path, which is adapted to orientate itself gravitationally, lowering the deflector to the bottom of the hole, bearing down on it by the drill rod line to wedge the deflector in the hole, withdrawing the line thereby snapping the suspending means and leaving the deflector wedged within the hole, drilling a pilot hole aligned with the path provided by the deflector; withdrawing the deflector, and reaming the pilot hole to correct size. v

Further according to the invention the deflector is wedged within the hole by awedge member initially secured to the deflector, the connection between the member and the deflector being broken by the downward pressure of the drill rod line, and the deflector being then propelled into wedging position by further downward pressure on the line.

Apparatus according to the invention comprises a deflector with a bore inclined to the axis of the deflector, and biased, when freely suspended, for the bore to he more nearly vertical than the axis; a wedge member having a spiked lower end; means, securing the wedge member to the deflector, adapted when the spiked end is in contact with the bottom of a borehole to shear when the deflector is subjected to a loading force, and means to suspend the deflector from a drill rod line.

Further according to the invention, the suspending means is adapted to be snapped under a tensile force less than that required to dislodge the wedged deflector.

An embodiment of the invention is described hereunder and illustrated in the accompanying drawings, in which Figure l is a longitudinal section (see section line II in Fig. 2) through a hole deflector,

Figure 2 is a perspective view of part of the deflector,

Figure 3 is a section through the lower end of a drill rod line, and

Figures 4 to 11 show successive stages in the redirection of a borehole.

The deflector shown in Figures 1 and 2 comprises an outer tube 11 having a bore defined by an inner tube 12.

bottom of the borehole.

The tube 12 is inclined to the axis of the tube 11 as shown. At the top left the space between the tubes 11 and 12 is filled with a counterweight 13. On the right both tubes are cut away for half their diameter to decrease the weight on the right hand side. At the top, the inner tube 12 has suspending holes 14 through which a copper wire 15 is threaded.

At the bottom, the deflector has a spiked wedge 17 which is adapted to move in the space between the tubes line XX. In other words, the bore of the tube 12 is 7 more nearly to the vertical (and as shown is vertical) than the aXis of the deflector.

The strength of the rivets 18 is such that they may shear when a loading force is applied at the top of the deflector and the end 20 of the wedge 17 is on the bottom of a borehole. The wire 15 is so chosen that it will snap under a tensile force less than that required to dislodge the wedged deflector.

Studs 21 on the wedge 17 act as stops to insure that on withdrawal of the deflector and after shearing of the rivets 18, the wedge is withdrawn with the deflector.

A core lifter 22 is provided in any conventional manner in a conical recess at the top of the tube 12.

The means by which the deflector is suspended for lowering down a borehole is illustrated in Figure 3. The deflector is suspended at the lower end 30 of a drill rod 31. The rod 31 is connected to the remainder of a drill rod line by means of a coupling 32 in a well known manner. The deflectoris hung from the loop of copper wire 15 which is hooked on to a length of chain 29 which, in turn, is fastened to a length of steel rod 34 having a thrust bearing 33 at its upper end. The bearing 33 is mounted on the coupling 32 through the medium of a compression spring 36 and a collar 35 on the rod "serves to prevent upwards displacement of'the assembly.

The latter position is illustrated in Figure 4. In this and the following figures the vertical has been shown as the line XX. The deflector is 40,,the bore serving as a guide is marked 41.

As indicated above, in Figure 4, the deflector 40 hangs freely from the rod 31. During further operations the deflector 40 is lowered and the wedge 17 contacts the The next step,'which is illustrated in Figure 5, is to bear down on the deflector 40 by means of the drill rod line. In this case the rod 31 applies a loading force to the deflector and shears the rivets 18. The deflector is now securely wedged in position since wedge 17 enters the earth at the bottom of the borehole and is itself thus firmly positioned to hold the deflector in place.

On withdrawal of the line the wire 15 snaps and leaves the deflector 40 in the hole as shown in Figure 6.

A string of rods is then made up the lower portion 42 of which is dimensioned to pass through and be guided by the bore 41 and which terminates in a drill bit 43. The rods are lowered into the borehole and rotated for 3 the bit to drill a pilot hole 4 4 aligned with the bore 41 (as shown in Figure 7) and thus more nearly vertical than the main body of the borehole.

On withdrawal the rod line engages the deflector at the core lifter 22 and engages on the line 42 so that the deflector is thus wedged to the line, whereupon the deflector, together with the wedge 17, which trails after it, are withdrawn from the hole as indicated in Figure 8.

The pilot hole 44 is then reamed in a known manner (Figures 9 and 10) and drilling proceeds down a hole which assumes more or less the configuration illustrated in Figure 11. V

In use it has been found that the apparatus of the invention will enable the borehole to be deflected approximately 195 at each operation. Boreholes which have deviated more than 5 from the vertical may be successfully dealt with, but below that figure the device tends to lose sensitivity because the inclination is insufiicient to ensure positive gravitational orientation of the deflector. For this reason the steps illustrated in Figures 7 to 11 are more or less diagrammatic. In practice the hole will deviate much more from the vertical X- -X and the hole 44 will not approximate the vertical as closely as shown-in the drawings.

In cases where deviations of'over 5' have taken place the invention has great practical utility.

What is claimed is:

1. 'Hole deflecting apparatus comprising a substantially tubular body, a bore in the body inclined to the axis of the body, and providing a passage for a pilot drill, a counterweight provided in, and at the upper end of, the body on the side which diverges from the bore to bias the body when freely suspended so that the bore is more nearly vertical than the axis of the body, a wedge member having a spiked lower end, means securing the wedge member of the body adapted to shear when the spiked end-is in contact with the bottom of a borehole and the body-is subjected to a loading force, guide means on the body to constrain relative movement of the Wedge member and the body when shearing has occurred to force the wedge to become firmly lodged between the body and the wall of the borehole to prevent rotation'of the body, means to prevent separation of the wedge member and the body'when the body 'is-moved upwardly in the borehole, and means to suspend the body from a drill rod line.

2. The "apparatus claimed inclaim 1 including a core 4 lifter adapted to permit downward movement of the drill through the here but to lock with the drill on upward movement thereof to permit removal of the apparatus from the borehole.

3. A borehole deflector having a substantially tubular body, a tube of lesser diameter than the body provided inside, the body and inclined to the axis of the body, a counterweight filling the upwardly diverging crescentshaped cavity between the tube and the body to bias the deflector when freely suspended so that the axis of the tube is more nearly vertical than the axis of the body, a wedge member havinga spiked lower end, means securing the wedge member to the body adapted to shear when the spiked end is in contact with the bottom of a borehole and the body is subjected to a loading force, guide means to constrain relative movement of the wedge member and the body when shearing has occurred to force the wedge to become firmly lodged between the body and the wall of the borehole to prevent rotation of the body, means to prevent separationof the wedge member and the body when the body'is moved upwardly in the borehole, and means to "suspend the body from a drill rod line.

4. The apparatus claimed in claim 3 including a core lifter adapted to permit downward movement of the drill through the bore but to lock with the drill on up ward movement thereof to permit removal of the apparatus from the borehole.

S. The apparatus claimed in claim 3 in which the suspending means i'sa loop "or copper wire.

6. The apparatus claimed in claim 3 in which the guide means includes a gap in the body substantially parallel to the principal axis thereof, the wedge means being positioned in part in the gap for movement therein.

7. The deflector claimed in claim 3 inwhich the body and inner tube are gap'ped over substantially half their circumferences for a substantial portion of their length at the side opposite to that at which the counterweight isprovided.

References Cited in the 'file of this patent UNITED sTATEs PATENTS 

